This invention relates generally to percutaneous electrical therapy systems for medical use. In particular, the invention relates to a percutaneous electrode entry angle control assembly and method for use with an electrical therapy system.
Electrical therapy has long been used in medicine to treat pain and other conditions. For example, transcutaneous electrical nerve stimulation (TENS) systems deliver electrical energy through electrode patches placed on the surface of a patient""s skin to treat pain in tissue beneath and around the location of the patches. The efficacy of TENS systems in alleviating pain is questionable at best, however.
More recently, a technique in which electrodes are placed through the patient""s skin into the target tissue has been proposed. Percutaneous Neuromodulation Therapy (xe2x80x9cPNTxe2x80x9d) (also sometimes called Percutaneous Electrical Nerve Stimulation or xe2x80x9cPENSxe2x80x9d) using percutaneously placed electrodes achieves significantly better pain relief results than TENS treatments using skin surface electrodes. This therapy is described in Ghoname et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation for Low Back Pain,xe2x80x9d JAMA 281:818-23(1999); Ghoname et al., xe2x80x9cThe Effect of Stimulus Frequency on the Analgesic Response to Percutaneous Electrical Nerve Stimulation in Patients with Chronic Low Back Pain,xe2x80x9d Anesth. Analg. 88:841-6 (1999); Ahmed et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation (PENS): A Complementary Therapy for the Management of Pain Secondary to Bony Metastasis,xe2x80x9d Clinical Journal of Pain 14:320-3 (1998); and Ahmed et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation: An Alternative to Antiviral Drugs for Herpes Zoster,xe2x80x9d Anesth. Analg. 87:911-4 (1998). The contents of these references are incorporated herein by reference.
Thus far, PNT practitioners have used percutaneously placed acupuncture needles attached to waveform generators via cables and alligator clips to deliver the therapy to the patient. This arrangement and design of electrodes and generator is far from optimal. For example, the prior art has not addressed the issue of how to control the entry angle of percutaneous electrodes used in PNT and other electrical therapies. It is therefore an object of this invention to provide electrode entry angle control in percutaneous electrical therapy systems.
It is a further object of this invention to provide a percutaneous electrical therapy system having electrodes and electrode assemblies that are safe, efficacious, inexpensive and easy to use.
Other objects of the invention will be apparent from the description of the preferred embodiments.
The invention is a percutaneous electrical therapy system with electrode angle of entry control. In a preferred embodiment, the system includes a control unit; an electrode electrically connectable to the control unit to deliver electrical therapy to a patient, the electrode having a sharp point at a distal end adapted to be inserted into a patient""s tissue; and an electrode angle of insertion assembly controlling the electrode""s angle of entry into the patient""s tissue. The electrode angle of insertion assembly preferably includes a housing supporting the electrode during insertion of the electrode into a patient""s tissue. In some embodiments of the invention, the housing has a distal face adapted to be placed on the patient to control the angle between the housing and the patient. The housing may also have an aperture in its distal face, the aperture being adapted to surround at least a portion of the electrode during insertion of the electrode into the patient""s tissue. In some embodiments, the distal face has a diameter greater than the housing""s diameter. Also, in some embodiments of this invention the electrode is adapted to move with respect to the housing during insertion of the electrode into the patient""s tissue.
There may also be a mechanical connection between the electrode and the housing during insertion of the electrode into the patient""s tissue. In some embodiments, the electrode and the housing are adapted to remain mechanically connected during application of electrical therapy to the patient. Also, the housing may be adapted to be separated from the electrode after insertion of the electrode into the patient""s tissue but before application of electrical therapy to the patient. The electrode angle of insertion assembly may also include a housing alignment member disposed on the patient""s tissue and adapted to mechanically interact with the housing to align the housing with respect to the patient""s tissue, such as a patch attached to the patient""s tissue. In the patch embodiment, the patch may be an annular member adapted to mate with the housing and to surround the electrode during insertion of the electrode into the patient""s tissue.
In some embodiments, the electrode angle of insertion assembly has an electrode actuator movable within the housing, the electrode actuator being adapted to move the sharp point of the electrode into the patient""s tissue.
Also, in some embodiments the system also includes an electrode insertion pain reducer adapted to reduce pain experienced by the patient during insertion of the sharp point of the electrode into the patient""s tissue.
The invention also includes the percutaneous electrode and electrode angle of insertion assembly described above apart from the control unit.
The invention is also a method of performing percutaneous electrical therapy including the steps of: aligning an electrode assembly housing with a patient""s tissue; inserting a sharp point of an electrode into the patient""s tissue, the housing supporting the electrode during insertion to control the electrode""s angle of insertion; and applying an electrical signal to the electrode from a control unit. In some embodiments, the aligning step includes the step of placing a distal face of the housing against the patient""s tissue. The placing step may include the step of attaching the distal face of the electrode assembly housing to the patient""s tissue.
In some embodiments, the method includes the steps of placing a housing alignment member on the patient""s tissue, wherein the aligning step comprising interacting the housing with the housing alignment member.
The invention is described in further detail below with reference to the drawings.